Knife with built-in sharpener



Dec. 21,1943.4 E. LQFRANK 2,337,158

KNIFE WITH BUILT-IN SHARPENER Filed May 7, 1943 /ME-ZMINVETR PatentedDec. 21, 1943 UNITED STATES PATENT OFFICE 8 Claims.

This invention covers certain improvements upon the self sharpeningknife as described and claimed in patent numbered 1,890,506, dated Dec.13, 1932, and issued to E. L. Frank et al., on a self sharpening knife,and the objects of this present invention are to provide certainimprovements in the original form of the invention as set out in thesaid patent, including improvements in the form of the handle, the bladebar carrying the blade, the means for releasa'bly locking the blade baror rod and integrally connected blade to their out-thrust position foruse, after the blade has been suitably sharpened through the use of theinvention, and the formation of the case or housing for holding thesharpening rolls as supported upon the leaf spring used for urging thesharpening rolls to the cutting edge of the knife blade.

Another object of the invention and the said improvements, is to providein a self sharpening knife, an elongated handle open through the sidesthereof and slotted through its ends to recipr-ocably engage a thincutting blade projected through the slot of the forward end of thehandle and integrally joined to a thin blade rod projected through theslot of the rear end of the handle and whereby the cutting blade may bereciprocated over sharpening devices mounted in the forward end of thehandle, the rear and protruded end of the blade rod being doubled backupon itself to form a stop adapted to Contact the rear end of the handlefor limiting the reciprocable movement of the blade in the process ofsharpening same, the said doubled rear end being compressible forinsertion through the slot of the rear end of the handle, and formed forlocking engagement thereat to hold the cutting vblade in its out-thrustposition for use after sharpening.

Still another object is to provide, in a self sharpening knife of thekind referred to, and including an open handle of elongated form andthrough which a cutting blade is reciprocably mounted from end to endthrough slots formed in the ends, and there being an elongated sharp-4ener slot formed through the under side of the handle at the forwardend thereofy a Sharpener element mounted through the said slot andadapted to enga-ge the cutting edge of the knife as it is reciprocatedthrough the said handle, the said Sharpener element being mounted upon aleaf spring anchored at its inner end to the outer side vof the handleat the rear end of the slot, and

lbeing formed at its forward end so as to fold up to provide bracketsadapted to operatively carry a pair of sharpening rolls to complete thesaid sharpening element.

With the foregoing objects and advantages in view, as also such other oradditional objects and advantages as may appear from the specification,attention `is directed tothe accompanying drawing as embodying preferredforms of the said improved knife, and wherein:

Figure 1 is a side elevation yof `a knife constructed in accordance withthis invention and improvements, the cutting blade being shown as fullyextended for use.

Figure 2 is a longitudinal vertical `section through the assembly asshown in Figure 1, the blade however being partially retracted, as inthe process of sharpening the same.

Figure 3 is a cross section on the line 3-3 of Figure 1.

Figure 4 is a cross section on the line 4 4 of Figure 1.

Figure 5 is a longitudinal cross section through the assembly as shownin Figure 1.

Figure 6 is a detail of the Sharpener element and rolls as supported inthe mounting brackets, the knife blade being also shown in section, aspositioned between the rolls, as in the process of sharpening the same.

Figure 7 is a detail showing a modified formation of the rear end of thedoubled blade supporting rod or strip.

Figure 8 is a plan view of the blank for forming the supporting bracketsof the Sharpener rolls.

This improved form of self sharpening knife comprises an elongatedhandle I, made of any suitable material, preferably integrally formedand with open sides as shown at 2. A blade receiving slot 3 is formedthrough the forward end of the handle and a blade rod receiving slot oflesser width is formed through the rear end of the handle in alignmentwith the slot 3. Finger depressions or holds 5 are formed on the sidesof the handle at the forward end thereof, on the margin-s of theopenings 2, and an elongated sharpener slot 6 is formed through theunder edge or side of the handle at its forward end. A thin, elongatedknife blade l, formed integrally with a thin, elongated and relativelynarrow blade rod 8, are together slidably mounted through the handle,through the slots 3 and Ll, with the blade 'l disposed in the forward.slot 3 and the blade rod 8 disposed in the rear slot 4. The rearwardlyprotruded end 9 of the blade rod 8, is doubled atly inward upon itself,as shown at iii, and the extremity thereof is reduced and turned sharplyoutward as at Il, to form a stop for the unit against the outer end ofthe handle as the unit is moved inwardly in the process of bladesharpening. The extremity II is reduced as shown in the drawing, and theslot 4 is widened at its lower end, in an offset relation as shown at4a, for receiving and passing the said outturned extremity or stop I I,-so that this stop may pass within the handle. The blade and blade rodbeing made of spring metal, the doubled and rearwardly protrudedportions 9 and Ill may be pressed together for passing them into andthrough the slots 4, 12a, or partially therethrough, where beingreleased, the out-turned extremity or stop Il will spring aside andengage the inner face of the end of the handle, as shown in Figures 1and 5, and thus releasably lock the blade 'I to its out-thrust positionfor use, and prevent its accidental retraction into the handle. On theother hand the shoulder of the reduced extremity Il, indicated at Ila,simultaneously contacts the outer face of the handle end, that is to saythe margin of the slot 4a, thus preventing the excessive projection ofthe knife blade 1. If preferred, the doubled end portion I may be madeof a separate and thinner strip of spring metal, as shown at I2 inFigure '7, and secured to the rearwardly protruded end of the blade rod8 by means of a rivet or screw I3, the strip I2 being joined to theouter face of the blade rod 8 and so located that the forward joined endof this element, or the forward margin thereof, will transversely alignwith the shoulder Ila thereof, thus providing additional stopping meansadapted to contact the lateral margin of the slot 4, for preventing theexcessive inward movement of the blade rod 8 and consequent excessiveoutthrust of the blade 1. When it is desired to renew the blade andblade rod, the rivet or screw I3 mai7 ibe removed, new elementsinserted, and then positioned and joined as above pointed out.

The sharpening unit referred to generally at I A, is made of a blank ofthin, spring steel as shown at I5 in Figure 6, and includes an elongatedspring strip IE, formed at its forward end and at opposite sides withears I'I and I8, and the latter having roller tabs I9 and 2D, extendedforwardly at one side and rearwardly at the other side, as shown. Theinner margins of the tabs I9, are out free from the strip I6 on thelines 2l. Thus as shown in the drawing the tabs I9, 2e are spaced apartlongitudinally on the strip I6. They are then turned up at right anglesto this strip, toward one another or toward a common plane, and the earsI'I, I8 being then also turned inwardly at right angles to the strip I6,the tabs I 9, 20 are brought squarely over onto the upper side of thestrip I5 in paralleled spaced and longitudinal alignment with eachother, thus completing the roller holder as indicated at 22. Knifesharpener rolls 23 are mounted in this holder side by side, on pins 24,and the tabs I9, 20 are notched as at 25, to accommodate the knife edgeas it is drawn back and forth between the rolls for sharpening.

The Sharpener unit so formed is mounted in place through the slot 6 ofthe handle by inserting the rolls 23 up therethrough, and then securingthe rear end of the spring strip I6 to the rear margin of the slot by arivet 26. The parts are so formed and positioned that with the blade 'Ifully extended, the rolls 23 will rest immediately back of the rear endof the blade and press up against the rod 8, thus holding the blade upagainst the handle in operative position. The blade is reinforced at itsjuncture with the blade rod by elongated half-round ribs 23 securedlongitudinally on each side of the blade rod and blade, and overlappingat their ends the juncture of the two. The end slots 3 and 4 of thehandle are then complementally enlarged as at 3b, 4b, to pass these ribsin the reciprocating movement of the blade and blade rod, in theoperation of sharpening the knife.

The foregoing description fully explains the construction and operationof the invention. To sharpen the knife blade the parts El and I arepinched together, thus permitting the inward rearward movement of theblade through the slot 4, the edge of the blade riding up and passingbetween the rolls 23 for sharpening the blade edge, a few reciprocationsof the blade suicing for the purpose. The blade rod is then thrust fullyinward by pinching together parts 9 and I0, and there locked, in themanner already pointed out.

While we have herein shown a particular embodiment of the invention andthe structural features thereof, this embodiment and these features maybe modified within the scope of the claims. The described improvementsprovide a simple, sanitary and practical knife, easily made through theintegral formation of the elements, and easily cleaned by virtue of theopen sided handle. New blades may also be readily inserted as may befound necessary.

I claim:

l. In a device of the kind described, an elongated, frame-like handle,formed open through its medial portion and having aligned slots formedlongitudinally through its ends, a thin cutting blade and a connectedthin blade rod passed slidably through the handle and through the endslots thereof, for reciprocable movement therethrough, and means on thehandle for sharpening the knife as it is so reciprocated.

2. In a device of the kind described, an elongated, frarne-like handleformed with a corresponding elongated opening through its medial portionfrom side to side, there being also a sharpening slot formed through theunder side of the forward end thereof and longitudinally aligned bladeslots formed through the ends thereof, the forward end margins of themedial opening through the handle at each side thereof being formed withfinger recesses, a combined thin knife blade and thin blade rod passedslidably through the handle and through the end slots thereof and thusadapted for reciprocable movement therethrough, the rearwardly protrudedend of the blade rod being doubled back upon itself to provide a stopagainst the outer end face of the handle to limit inward movement of therod in the process of blade sharpening, and means seated through thesaid sharpening slot at the forward end of the handle for sharpening theknife blade as it is reoiprocated through the handle.

3. In a device according to claim 2, the extremity of the doubled backrear end of the blade rod being reduced to form an outer stop shoulderagainst the end of the handle, and a cooperative means for releasablylocking the blade rod to its innermost position and the knife blade toits out-thrust position for use, the said co-operative means includingthe doubled structure at the rear extended end of the blade rod.

4. In a device according to claim 2, the knife blade being relativelywider than the blade rod and the end slots of the handle beingproportioned to correspond therewith, the extremity of the doubled backrear end of the blade rod being reduced and turned outward to form aninner stop, the shoulder of this reduced extremity forming an outerstop, the rear end slot of the handle being formed with a laterallyoffset extension to permit the reduced extremity 0f the doubled backrear end and stop of the blade rod to pass therethrough, on thecompression of this doubled end of the blade rod, and whereby theelements may be releasably locked with the knife blade projectedforwardly for use to its limited extent.

5. In a device according to claim 2, the said sharpening means as seatedthrough the said sharpening slot of the handle comprising an integrallyformed, elongated spring strip having spaced roll holding tabs thereonand sharpening rolls mounted between the tabs, at the forward end of thestrip, the said strip being secured at its rear end to the under side ofthe handle and the sharpening elements being passed upward through thesharpening slot in such position that the cutting edge of the knifeblade will ride up between the sharpening rolls as the knife blade isdrawn back and forth thereover.

6. In a device according to claim 1, elongated reinforcing ribs securedlongitudinally at each side of the juncture of the cutting blade andblade rod.

7. In a device according to claim l, elongated reinforcing ribs securedlongitudinally at each side of the juncture of the cutting blade andblade rod, the said end slots of the handle being complementallyenlarged to pass the ribs on the reciprocating movement of the blade andblade rod.

8. In a device of the kind described, a blank for forming up into theSharpener roll supporting element referred to, the said blank includingan elongated spring strip formed at its forward end and at oppositesides with transversely aligned ears, the latter having pendentlyconnected roller supporting tabs, one extended forwardly at one side andthe other extended rearly at the other side, and thus arranged forturning up perpendicularly to and transversely across the upper face ofthe spring strip, in spaced relation one to the other, for supportingSharpener rolls therein between, at each side of the spring strip.

EARL L. FRANK;

